Surgical cutting instruments are useful for a variety of surgical procedures designed to remove or repair healthy or diseased tissue. The tissue may be soft tissue such as muscle, or the tissue may be bone. Certain specific procedures are useful to remove polyps, a uterus (hysterectomies), cancer, tonsils, fibroids, and the like. If tissue is vascularized, the cutting instrument may also cauterize the tissue to reduce bleeding.
One procedure for removing tissue is a “hysterectomy,” which removes reproductive organs of a female, particularly the uterus. A typical hysterectomy can be performed using an open abdominal process, which provides open access and clear view of the organs in question. However, an open abdominal incision increases the risk of injury and infection.
As an alternative, the vaginal canal can be used to reach the uterus, but removing the uterus through the vagina requires also removing the cervix which is not always desirable. It is generally preferred that as little tissue as possible be removed and it is understood that where possible it is best to not disturb the cervix.
At present, laparoscopic methods can be preferred for a hysterectomy, based on improved safety, brevity, reduced recovery time, reduced blood loss, and reduced risk of complications. A laparoscopic hysterectomy can require only very tiny incisions in the abdomen. Among various versions of laparoscopic hysterectomy procedures are those in which an electrical cutting knife and cauterizing tool is used to separate tissue and organs from where they are attached.
For cutting and cauterizing tissue, uterus tissue or otherwise, an electrode-tipped surgical instrument can be used. In a hysterectomy in particular, electrode-tipped instruments have been used to cut the uterus from the cervix at the uterine isthmus, which is the inferior-posterior part of uterus on the cervical end of the uterus, a location at which the uterine muscle is narrower and thinner. In some cases, ovaries are cut away from their attachment to the uterus, e.g., at the fallopian tubes, and are left within the patient while the uterus is removed. Alternately, a surgeon may desire to keep the ovaries with the uterus, separate the ovaries from their attachment to the body, and remove the ovaries with the uterus.
To separate tissue for removal, a surgeon can use a tip of an electrical knife to apply electrical current to the region of tissue where resection is desired. In various conventional surgical cutting instruments, an electrical knife can be arranged as a monopolar system having a single electrode at the instrument tip. A patient's body or bulk tissue forms an electrically conductive path to a second electrode of opposing pole (sometimes referred to as a “ground” or “earth”). Current density may be very high at the knife edge, but very low at the grounding electrode. Accordingly, cutting and cauterization only occur at the tip of the instrument with very little or negligible damage to tissues near the other electrode which is spread over a considerably large area.
While monopolar systems are considered safe, the use of these systems includes undesirably passing electrical currents through healthy tissue. As an alternative, bipolar electrical cutting systems are sometimes arranged with both electrodes incorporated in the cutting instrument tip. In this way, electrical current passes from the first electrode, briefly through a small portion of tissue, and thereafter returns at the electrode of opposite pole. The electrical current only interacts with a very small volume of tissue, and specifically with the portion of tissue intended to be manipulated (cut or cauterized). Because of this, bipolar systems are sometimes preferred as more efficient and safe.
Laparoscopic surgical techniques allow for surgical procedures to remove large organs through very small abdominal incisions. In a laparoscopic surgery, small abdominal incisions are made and prepared with special port systems to allow elongate surgical instruments not larger than about 10 mm to about 15 mm in cross-section to be inserted into the abdominal cavity. Video cameras (with lighting), cutting instruments, grabbing tools, among others, are inserted via these abdominal ports and a surgeon manipulates them to operate various organs and tissues. After organs are removed via a laparoscopic surgery, a patient quickly and easily heals as there is considerably less damage to the abdominal wall. Further, operating times are often reduced, thus improving efficiency.
A laparoscopic supracervical hysterectomy can include cutting a uterus away from fallopian tubes, and a blood supply for the uterus. After the uterus is separated from of these and any other connective tissue, the uterine tissue can be severed at a location near the cervix. In common laparoscopic processes, an electrical knife may be used to first resect one side of the uterus, and then the opposite side, to fully sever the circular tissue of the uterus near the cervix. The steps required to manipulate and cut the uterus from separate sides of the organ can be difficult and can require a considerable amount of surgical time.
To improve on positioning a cutting element relative to tissue of a uterus, certain tools have been developed. See for example U.S. Pat. No. 5,078,716 and United States Patent Application 2009/0182324. Among previous tools are instruments that including an open loop wire that can be guided around tissue of a uterus by a specially shaped “introducer.” After the “wire” is routed properly, the loop is closed by fastening the wire ends to special hardware provided for such. Application of current causes the uterus to be sectioned in a single plane leaving a preferred cut. The resection step is quick and smooth, but the instrument involves considerable effort to first properly thread the cable around the uterus, and still further to couple the cable ends to the tool sockets in order to realize a closed-loop before application of electrical current.
Other tool alternatives includes a retractable loop that must be placed around the uterus by enlarging the loop and passing the closed loop over the fundus (top) of the uterus. In practice, the need to pass the enlarged closed loop over the fundus of the uterus, and to move the closed loop to isthmus (base) of the uterus, can be challenging.